Viral Gastroenteritis: Introduction

Overview and Implications

Viral Gastroenteritis

Gastroenteritis is an inflammation of the lining of the stomach and intestines, causing an acute onset of severe vomiting and diarrhea (Centers for Disease Control and Prevention (CDC) 2010). Infections that cause gastrointestinal illness (GI) may be caused by a variety of agents including bacteria, viruses and protozoa. Outbreaks of infectious GI can be devastating and lead to significant increased costs, increased patient morbidity, and in some instances patient mortality. The most important characteristic of pathogens responsible for infectious gastroenteritis is their ability to be rapidly transmitted in healthcare settings among individuals who often are highly susceptible. Episodes of infectious gastroenteritis account for a significant proportion of all patients/residents/clients in healthcare settings who develop diarrhea with or without nausea and/or vomiting (Provincial Infection Control Network of British Columbia 2016).

Healthcare-associated infections (HAIs) are defined as infections that occur as a result of healthcare interventions in any healthcare setting where care is delivered (Provincial Infectious Diseases Advisory Committee (PIDAC) & Ontario Agency for Health Protection and Promotion 2012). HAIs, such as gastroenteritis, result in a substantial burden of disease in Canadians, and are an important hospital and public health concern in Canada (PIDAC & Ontario Agency for Health Protection and Promotion 2014; Public Health Agency of Canada (PHAC), 2012)

The Clinical Group "Viral Gastroenteritis" in the Hospital Harm Indictor focuses only hospital associated gastroenteritis caused by viral agents such as rotavirus, norovirus, adenovirus.

Rotaviral enteritis

Rotaviruses are the most common cause of severe diarrhoeal disease in young children throughout the world. According to WHO estimates in 2013 about 215,000 children aged under five years die each year from vaccine-preventable rotavirus infections; the vast majority of these children live in low-income countries (World Health Organization (WHO) 2018).

Rotavirus disease is characterized by vomiting and watery diarrhea for three to eight days. Fever and abdominal pain also are common. Additional symptoms include loss of appetite and dehydration. Symptoms usually start about two days after a person is exposed to rotavirus. Vomiting and watery diarrhea can last three to eight days. (CDC 2019b).

Rotavirus infections are generally more severe and clinically significant in children aged three to 35 months. Adults tend to be asymptomatic and/or may demonstrate subclinical infection. Immunocompromised individuals are susceptible to developing more severe disease manifestations (PHAC 2010).

Chances of spread of infection within hospitals are high. Nosocomial infections are common and are a major cause of diarrhoea in newborns and infants. Several outbreaks have been observed in geriatric groups within hospitals. The most common mode of transmission for rotavirus is through faecal-oral spread, either from person-to-person or contact with contaminated environmental surfaces. The possibility of spread through faecally contaminated food and water also exists. Transmission through respiratory droplets has also been suggested; however, more investigation is required. Health Canada has approved RotaTeq and Rotarix vaccines in Canada; however, they are not part of the routine immunization programs that are currently available (PHAC 2010).

Acute gastroenteropathy due to Norwalk agent

Norovirus is the official genus name for the group of viruses provisionally described as "Norwalk-like viruses" (CDC 2011). Norovirus causes acute gastroenteritis (CDC 2019c).

Norovirus illness is usually brief in people who are otherwise healthy. Young children, the elderly, and people with other medical illnesses are most at risk for more severe or prolonged infection. Like all viral infections, noroviruses are not affected by treatment with antibiotics (CDC 2010).

Norovirus is characterized by rapid onset of nausea, vomiting, diarrhea, abdominal cramps, abdominal pain, mucus in stool, malaise, headache, and fever (PHAC 2017). Diarrhea is more common in children and vomiting is more common in adults. In some cases, people develop dehydration because they are unable to drink enough liquids to replace the liquids they lost from frequent vomiting and diarrhea (CDC 2010).

Up to 30 per cent of Norovirus infections are asymptomatic, however, these individuals are able to transmit the virus (PHAC 2017). Noroviruses are found in the feces and vomit of infected people (CDC 2010). Norovirus transmission is usually person to person through the fecal-oral route. It can also be transmitted through the environment, contaminated surfaces, food, water, fomites, and aerosols (PHAC 2017).

Norovirus infections are very contagious and spread very rapidly. Healthcare facilities and other institutional settings (e.g., daycare centers, schools, etc.) are particularly at-risk for outbreaks because of increased person-to-person contact (CDC 2010; PHAC 2017).

Adenovirus

Adenoviruses can cause a wide range of illnesses such as common cold or flu-like symptoms, fever, sore throat, pneumonia, conjunctivitis, and acute gastroenteritis. Adenoviruses can cause mild to severe illness, though serious illness is less common. People with weakened immune systems, or existing respiratory or cardiac disease, are at higher risk of developing severe illness from an adenovirus infection. Adenoviruses are usually spread from an infected person to others through:

close personal contact, such as touching or shaking hands
the air by coughing and sneezing
touching an object or surface with adenoviruses on it, then touching your mouth, nose, or eyes before washing your hands
an infected person's stool, for example, during diaper changing.

Adenoviruses are resistant to many common disinfectants and can remain infectious for long periods on environmental surfaces and medical instruments.

Some people infected with adenoviruses, especially those who have weakened immune systems, can have ongoing infections in their tonsils, adenoids, and intestines that do not cause symptoms. They can shed the virus for weeks or longer. (CDC 2019a)